How To Reduce Fishing Mortality

Transcription

1 Fisheries Release Mortality: Identifying, Prioritizing, and Resolving Data Gaps L. R. Benaka, L. Sharpe, L. Anderson, K. Brennan, J. E. Budrick, C. Lunsford, E. Meredith, M. S. Mohr, and C. Villafana U.S. Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service NOAA Technical Memorandum NMFS-F/SPO-142 July 2014

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3 Fisheries Release Mortality: Identifying, Prioritizing, and Resolving Data Gaps L. R. Benaka, L. Sharpe, L. Anderson, K. Brennan, J. E. Budrick, C. Lunsford, E. Meredith, M. S. Mohr, and C. Villafana NOAA Technical Memorandum NMFS-F/SPO-142 July 2014 U.S. Department of Commerce Penny S. Pritzker, Secretary National Oceanic and Atmospheric Administration Kathryn D. Sullivan, Administrator National Marine Fisheries Service Eileen Sobeck, Assistant Administrator for Fisheries

4 Recommended citation: Benaka, L. R., L. Sharpe, L. Anderson, K. Brennan, J. E. Budrick, C. Lunsford, E. Meredith, M. S. Mohr, and C. Villafana Fisheries Release Mortality: Identifying, Prioritizing, and Resolving Data Gaps. U.S. Dept. of Commer., NOAA. NOAA Technical Memorandum NMFS- F/SPO-142. Copies of this report may be obtained from: National Marine Fisheries Service National Oceanic and Atmospheric Administration National Observer Program (attn. Lee Benaka) 1315 East-West Highway, 12 th Floor Silver Spring, MD Or online at: ii

5 Table of Contents Dedication v Executive Summary... vi 1. Introduction Background NMFS-Funded Release Mortality Research by Region Northeast Southeast West Coast Alaska Pacific Islands How Release Mortality Assumptions Are Incorporated into Stock Assessments Approaches to Developing Revised Release Mortality Assumptions Delphi Technique Model-Based Approach Identification and Prioritization of Data Gaps Identification and Prioritization of Species-Specific Research Needs West Coast Examples Southeast Examples Northeast Examples Best Practices and Techniques for Release Mortality Research Outreach Tagging Arrays Estimating Mortality Rates Using Chamber Studies, Cage Studies, and Acoustic Tagging Application of Mortality Rates in Management Identifying Components of a National Release Mortality Science Strategy Conclusion: Next Steps for Addressing Broader Release Mortality Issues References...53 iii

6 Appendix A Release Mortality Workshop Attendees (September 25-26, 2013)...56 Appendix B Summary of NMFS-Funded Release Mortality Research by Region...57 Appendix C Compilation of Release Mortality Estimates Used by NMFS...66 iv

7 Dedication The authors would like to dedicate this report to the memory of Karen M. Burns. Beginning in the 1990s, Dr. Burns conducted numerous helpful and influential studies of release mortality in Southeast reef fishes. She was missed during the development of this report, but her work continues to inspire release mortality research. v

8 Executive Summary Recreational and commercial fisheries face continued effort restrictions due to high fishing mortality and slow stock rebuilding processes. Regional fishery management councils have implemented short fishing seasons, closed areas, species-specific non-retention measures, and size limits in response to overfished declarations. Under these restrictive management systems, release mortality and barotrauma can occur, which impedes the rebuilding of overfished stocks. Some fishermen believe that the use of fishing practices and technologies designed to minimize barotrauma and post-release mortality should reduce overall fisheries mortality and in turn lead to increased fishing opportunities. This report describes research projects addressing release mortality that were funded by NOAA s National Marine Fisheries Service (NMFS) from 1999 to The projects highlighted in this section are not a complete accounting of all NMFS-funded release mortality research during this timeframe, but these projects do reflect the large majority of projects funded and research areas. The number of NMFS-funded research projects varies by region: Northeast (17), Southeast (24), West Coast (8), Alaska (4), and Pacific Islands (1). This report focuses on various approaches to incorporating release mortality assumptions into stock assessments, as well as techniques that have been used in the Northeast (Delphi Technique) and the West Coast (model-based approach) to develop revised release mortality estimates. In September 2013, scientists from within and outside of NMFS attended a workshop to help NMFS identify and prioritize data gaps related to discard mortality estimates and related stock assessment issues. Workshop attendees identified and prioritized several important release mortality data gaps, including: Development of baseline discard mortality information, including an understanding of underlying factors and their interactions. Measurement of release mortality in fishery, as opposed to lab, conditions. Development of reliable and robust proxies for mortality (both short- and long-term). Examination of unaccounted escapement mortality. Identification of optimal sampling designs for accuracy and precision of discard mortality estimates. Communication of how discard mortality estimates are calculated and used, and how they affect stock assessments, annual catch limits, and management. Workshop participants agreed on a list of seven high-priority criteria that should help direct scientists and managers in focusing release mortality resources on particular species. This report discusses several species in terms of these high-priority criteria. This report also discusses best practices and techniques related to release mortality research, especially effective outreach efforts related to release mortality research, as well as tagging and the related issue of acoustic arrays. Finally, this report identifies some components of a national release mortality science strategy and describes next steps for addressing broader release mortality issues. vi

9 1. Introduction Recreational and commercial fisheries face continued effort restrictions due to high fishing mortality and slow stock rebuilding processes. The National Oceanic and Atmospheric Administration s (NOAA) National Marine Fisheries Service (NMFS) is committed to rebuilding overfished fish stocks. The NMFS Status of Stocks 2012 Report identified several important recreational and commercial fish stocks as overfished, including: Atlantic cod; Northeast winter and yellowtail flounder stocks; various Atlantic marlin, tuna, and sharks; red snapper in the South Atlantic and Gulf of Mexico; and some Pacific rockfish stocks. Regional fishery management councils have implemented short fishing seasons, closed areas, species-specific non-retention measures, and size limits in response to overfished declarations. Under these restrictive management systems, barotrauma and release mortality can occur, which impedes the rebuilding of overfished stocks and can limit fishing opportunity. The term release mortality refers to the incidence of mortality after a fish has been discarded. ( Discard mortality is often an interchangeable term.) A variety of factors can increase release mortality, including how the fish is handled and whether it is exposed to air, is injured during the fishing process, or experiences thermal shock during ascent. Release mortality can occur soon after discarding, due to severe injury or immediate post-release predation, or it can be prolonged; for example, if a fish s internal organs have been damaged prior to release, mortality caused by starvation can take a week or longer. In addition, the concept of release mortality encompasses boarding morality, which occurs when a fish is dead or near-dead when it is brought on board and then subsequently discarded. Barotrauma results from a change in pressure as some deep-water fish, especially fish with physoclistous gas bladders, are rapidly brought to the surface. The symptoms of barotrauma, including stomach eversion and bulging eyes, have been described extensively in literature, especially for Pacific rockfish (for example, Jarvis and Lowe 2008, Hannah et al. 2012). Fishermen around the country have adopted various fishing practices, including venting and descending devices, which are designed to minimize the effects of barotraumas. These methods have only been tested for success or ease of use for a handful of species to date. Where they have been tested, descending devices have been shown to substantially reduce mortality due to barotrauma or predation and thus aggregate release mortality (Jarvis and Lowe 2008, Hannah et al. 2012, PFMC 2012, PFMC 2013, PFMC 2014). This reduction in mortality has been quantified for three species of West Coast rockfish, and these mortality rates will be incorporated into recreational fisheries management systems in Washington, Oregon, and California for 2013 and beyond (PFMC 2014). Further research may lead to accounting for reduced mortality in additional species and deeper depths when a descending device is used. The recreational fishing community has raised the issue of barotrauma and recreational release mortality as a concern over the past few years. Fishermen and managers have developed and promulgated best practices designed to reduce post-release mortality (e.g., through the FishSmart website Barotrauma and release mortality also are concerns in commercial fisheries. Some fishermen believe that the use of fishing practices and technologies designed to 1

10 minimize barotrauma and post-release mortality should reduce overall fisheries mortality and in turn lead to increased fishing opportunities. Fisheries release mortality is a concern not only in the United States, but also in Europe. In response to a request from the European Commission, the International Council for the Exploration of the Sea established a Workshop on Methods for Estimating Discard Survival in January This Workshop was tasked to, among other things, (1) develop guidelines and, where possible, identify best practices for undertaking discard survival studies; (2) identify approaches for measuring and reducing, or accounting for, the uncertainty associated with mortality estimates; and (3) critically review current estimates of discard mortality (ICES 2014). Fishermen and managers are asking what changes in management, especially related to quotasetting and fishery restrictions, should occur if best practices and technologies are being used to reduce post-release mortality and the effects of barotrauma. If more fish released or discarded in recreational and commercial fisheries are likely to survive, then long-standing release mortality assumptions used for fisheries management and stock assessments may need to be re-examined. Ultimately, fishermen expect that they should be allowed increased access to fish if their fishing practices lead to an improvement in survival rates for discarded or released fish. Alternatively, reduced mortality will help rebuild stocks faster than otherwise, although using estimated conservation benefits for stock rebuilding or increasing fishing opportunities for healthy stocks that co-occur with overfished species is a policy decision for each regional fishery management council. The intent of this paper is to review release mortality initiatives by region; identify, prioritize, and try to resolve data gaps; and identify components of a national post-release mortality science strategy. This paper also includes a discussion of best practices and techniques for release mortality research. 2

11 2. Background NMFS has been increasingly focused on best fishing practices to reduce release mortality and barotrauma since the late 2000s. In June 2008, NMFS and the Gulf of Mexico Fishery Management Council implemented Amendment 27 to the Fishery Management Plan for the Reef Fish Resources of the Gulf of Mexico. This amendment required the use of non-stainless-steel circle hooks when using natural baits to fish for Gulf of Mexico reef fish, and it required the use of venting tools and dehooking devices for fishermen participating in the commercial and recreational reef fish fishery. Outreach and education efforts regarding the use of descending devices to mitigate mortality of discarded West Coast rockfish started in Since then, more than 50,000 copies of the Bring That Rockfish Down brochure, and hundreds of descending devices, have been distributed to anglers, tackle shops, and fishing clubs throughout California by the California Department of Fish and Wildlife, in collaboration with California Sea Grant and fishing clubs. Similar outreach was conducted soon after in Oregon and Washington, and efforts in all three states are expected to continue to educate the fishing public and increase documented rates of descending device use. In September 2009, NMFS initiated a Recreational Fisheries Initiative to strengthen its partnership with the saltwater recreational fishing community. This initiative led to an April 2010 Recreational Saltwater Fishing Summit and an October 2010 Recreational Saltwater Fisheries Action Agenda. The Action Agenda included five signature issues, one of which focused on cooperative research and monitoring, including the engagement of the recreational community in addressing barotrauma issues through a joint NMFS stakeholder workshop. Beginning in 2011, NMFS funded an initiative called FishSmart a sportfishing-driven program focused on communication with anglers, researchers, and partners. In March 2011, FishSmart held a National FishSmart Workshop on Improving the Survival of Angler-Caught and Released Fish, which focused on barotrauma. FishSmart subsequently held three regional workshops on improving survival of angler-caught and released fish in recreational fisheries for the Gulf of Mexico/South Atlantic (April 2012), Pacific (May 2012), and Mid-Atlantic/New England (March 2013). In March 2013, the NMFS National Policy Advisor for Recreational Fishing provided resources to the NMFS Office of Science and Technology to develop this white paper. The development process for this white paper included a September 2013 workshop attended by scientists from within and outside of NMFS, which was designed to provide background information for this white paper. Appendix A lists the workshop attendees. 3

12 3. NMFS-Funded Release Mortality Research by Region This section describes research projects addressing release mortality that have been funded by NMFS since the late 1990s. This section s projects are not a complete accounting of all NMFSfunded release mortality research during this timeframe, but these projects do reflect the large majority of projects funded and research areas. Appendix B summarizes these research projects in a table. 3.1 Northeast Past Projects Discard Mortality Estimation of the Southern New England Flatfish Complex using Reflex Action Mortality Predictor (RAMP) Methods This Cooperative Research Program project, completed in 2012, examined factors related to discard mortality for yellowtail flounder (Limanda ferruginea), winter flounder (Pseudopleuronectes americanus), and windowpane flounder (Scophthalmus aquosus). The Southern New England Mid-Atlantic yellowtail flounder stock has a history of substantial discards, and the current stock assessment assumes 100% discard mortality. This project used a controlled experimental trawl to test seven reflex actions from stressed and unstressed yellowtail flounder. Tow time and air exposure were tested to identify their effect on mortality. Mortality was significantly related to reflex impairment. Exposure to air was the more influential stressor in the survivability of yellowtail flounder, suggesting that the discard mortality could be reduced in the fishery by limiting the time the fish are exposed to air on deck. For winter flounder, investigators used a controlled experimental trawl to test seven reflex actions from stressed and unstressed winter flounder. Tow time and air exposure were tested to identify their effect on mortality. Mortality was significantly related to reflex impairment, but neither air exposure nor tow time significantly affected the survivability of winter flounder. Although air exposure did not significantly affect survival, none of the experimental fish exposed to air for 15 minutes or more survived, suggesting that the discard mortality could be reduced by limiting the length of time the fish are on a dry deck. Likewise, for windowpane flounder, investigators used a controlled experimental trawl to test seven reflex actions from stressed and unstressed windowpane flounder. Tow time and air exposure were tested to identify their effect on mortality. Mortality was not significantly related to reflex impairment, and neither air exposure nor tow time significantly affected the survivability of windowpane flounder. These results indicate that windowpane flounder are highly susceptible to the stresses of the commercial fishing process and are unlikely to survive discarding regardless of the sampling or handling method. A paper based on this research (Barkley and Cadrin 2012) applied RAMP monitoring to demonstrate a 42 73% range of yellowtail flounder discard mortality estimates from the southern New England trawl fishery. 4

13 Optimizing the Georges Bank Scallop Fishery by Maximizing Meat Yield and Minimizing Bycatch This Atlantic scallop research set-aside project, completed in 2012, attempted to determine discard mortality rates for yellowtail and winter flounder in the Georges Bank scallop fishery. This project s estimates of yellowtail flounder RAMP score for the scallop fleet indicated that the estimated discard mortality rates ranged from 64 to 90%. The time series of discard mortality estimates and confidence intervals (excluding 3 months) showed a fairly stable estimate of discard mortality near 85%. Based on the RAMP results, and the possibility for additional sources of mortality not accounted for by the RAMP method, investigators agreed to assume a discard mortality of 90% for the southern New England/Mid-Atlantic yellowtail flounder stock assessment. Investigators also tested reflex actions on 586 winter flounder. The mean RAMP score was 0.57, which correlated to a discard mortality estimate of 36%, with lower and upper confidence intervals of 16% and 60%. This estimate of discard mortality for winter flounder in the scallop fishery (36%) is lower than the currently assumed 50% for all commercial fishing. The accepted value of 50% fell within the investigators confidence interval range, indicating that the 50% used in the stock assessments may not be an overestimate for the scallop fleet. Although the basis of the 50% discard mortality assumption is not well documented, it appears to be an approximation based on an estimate of discard mortality of yellowtail flounder off Canada. This project shows that the currently accepted value used in the winter flounder stock assessments may be an accurate representation of the true discard mortality rate for the scallop industry Evaluation of Summer Flounder Discard Mortality in the Bottom Trawl Fishery, Part II: A Study of the Offshore Winter Fishery This Cooperative Research Program project, completed in 2012, was designed to determine summer flounder discard mortality relative to tow time, fish size, and the amount of time fish were on the deck of the vessel. Investigators conducted tows of 1, 2, and 3 hours in duration. Investigators culled fish both immediately (from 0 to 10 minutes on deck) and after being held on deck longer (25 to 35 minutes on deck). As soon as the fish arrived at the dock, investigators transferred live fish to a shore-side holding system and monitored them for mortality over a 21- day period. Discard mortality rates were calculated based on the live/dead fraction of fish sorted on deck as well as the mortality rate of the live fish held in the holding system over the 21-day monitoring period. The main driving factor in all analyses of live/dead fraction on deck was cull time. The fraction live is clearly impacted by the time it takes to cull the fish. At and beyond the 35 to 50 minute interval, fish begin to die off rapidly, no matter the tow time or catch weight. Jumbo-sized fish survived the best during the extended monitoring period, while small fish survived the worst. The on-deck original condition of fish was significant for mortality over 21 days. Ambient on-deck air temperature at time of capture significantly impacted mortality during the extended monitoring period. Warmer on-deck air temperatures were associated with better survival. Overall median discard mortality was calculated to be 97.65% much higher than the current assumed rate of 80% used in the stock assessment. Overall mean discard mortality was 80.4% and was nearly identical to the value assumed in recent summer flounder 5

14 assessments. The discard mortality determined by this study should be considered a minimum mortality rate Summer Flounder Discard Mortality in the Inshore Bottom Trawl Fishery This Cooperative Research Program project, completed in 2011, was designed to evaluate actual trawl discard mortality of summer flounder (Paralichthys dentatus) within a research design for comparison to the assumed discard mortality rate currently used in the stock assessment. The study goal was to determine discard mortality relative to tow time, total catch, fish size, and the amount of time that fish were on deck. Initially, investigators conducted 10 scientific fishing trips consisting of tows of 1, 2, and 3 hours in duration. Investigators culled fish at consistent time intervals into live and dead on deck. Additionally, a sub-sample of live fish from the immediate cull and the delayed cull were held in an on-board live system and then transferred to an extended mortality monitoring net pen system. The overall summed discard mortality as determined by this project had a mean of 64.6% and a median of 78.7%. The mean discard mortality in the 1-hour tows was 58%, in the 2-hour tows 61%, and in the 3-hour tows 77%. When comparing the parameter values of tow time, cull time, and total catch as determined by this study, it is apparent that shorter tows, faster culling, and improved handling practices, while reducing per-tow total catch, can reduce summer flounder discard mortality The Design, Development, and Field Testing of an Innovative Circular Net Pen to be Used to Assess Bycatch Mortality of Atlantic Cod at Sea This Cooperative Research Program project, completed in 2010, involved the design and testing of an open-net system to study discard mortality at sea. The net pen was tested for a 24-hour period in September During this period, the net was deployed and retrieved 15 minutes later and then re-deployed for 24 hours before final retrieval. The pen was redeployed for 30 hours in April During this experiment, 40 trawl-caught cod were placed in the net. A video camera was inserted into the pen, and cod were actively seen swimming within the net. Moreover, it appeared that individual cod were using the net at different depths to recover from the trawling process. During the deployment times, the structural integrity of the net was maintained, even when the sea wave-height increased to 2 4 feet for an extended period of time and with the tethering vessel anchored to the sea floor. Based on the success of the net design and the ability for cod to use the net to recover from the trawling process, the investigators concluded that the net can be deployed for any length of time under the same sea conditions to study discard mortality in a variety of fish species Discard Mortality in the Summer Flounder Fishery: A New Approach to Evaluation This Cooperative Research Program project, completed in 2008, was designed to determine the discard mortality, including latent mortality, for summer flounder in the otter trawl fishery in the Mid-Atlantic Bight. At the time of this study, scientists assumed 80% summer flounder discard mortality from the commercial fishery. The investigators tested the effectiveness of motion- 6

15 sensitive tags in determining discard mortality in the laboratory, estuary, and ocean. The investigators found that motion-sensitive tags could provide another means for interpreting mortality in tagged discards. Vertical movement has also shown to be potentially useful when determining mortality of a fish using acoustic telemetry over both field studies in 2009 and To test the assumption that it is possible to distinguish between live and dead tagged fish using telemetry, the investigators tracked fish in a preliminary effort in an estuary and evaluated their behavior in the laboratory. These studies showed that dead summer flounder (carcasses) can move substantial distances, and did so in synchrony with tidal currents. Live fish were much less mobile and more directed in their movements. In order to determine the mortality of these discarded fish, both live and dead summer flounder were tagged and released in a fixed hydrophone array on September 15, 2009, at a location off Brigantine, New Jersey. Initial results from commercial fishery length tows showed most fish in a poor to intermediate health condition. The initial on-deck mortality was 32.7%. Mobile tracking efforts were able to re-detect both initially live and dead fish during tracking, and within the array for approximately 24 hours before a northeast storm event. Fish of poor initial health re-detected after the storm were found in a relatively concentrated area about 8 km southwest of the release site, while live fish exited the array as they moved offshore as typical of the fall migration. These movement patterns provide a latent mortality estimate of 50%. The final discard mortality estimate, combining on-deck mortality and latent mortality, is 82.7% Industry-Science Partnership Investigating the Short-Term and Long-Term Discard Mortality of Spiny Dogfish Using Hook Gear in Gulf of Maine Waters This Cooperative Research Program project, completed in 2007, was a partnership between the Gulf of Maine Research Institute (GMRI), the Cape Cod Commercial Hook Fishermen s Association (CCCHFA), and commercial fishermen. The primary research objective was to investigate the short-term discard mortality rate of dogfish from different commercial hook gears. Survivability was investigated through caging studies. A total of 2,418 dogfish were sampled between the two regions; of these 682 were caged by GMRI (45% males and 55% females) and 1,234 were caged by CCCHFA (27% males and 73% females). An overall regional difference in short-term discard mortality was observed; GMRI recorded significantly lower total mortality (7%) than CCCHFA (22%). Regional, averaged findings showed a sex effect with males demonstrating higher mortality (26%) than females (14%). The largest dogfish of each sex demonstrated greater resilience to mortality. Gear effects were found, with highest mortality resulting from longline gear (22%), while the different hand gear related mortality ranged from 8 17%. The relationship between hook removal treatment and hooking severity index was significant. Because this study s long-term discard mortality assessments were aborted for logistical reasons, these findings represent the range of likely short-term discard mortality from hook gears across the region. 7

16 Juvenile Bycatch and Survival Assessment of Spiny Dogfish (Squalus acanthias) in a Western Atlantic Trawl Fishery This 2003 Saltonstall-Kennedy (S-K) Grant Program project, completed by the New England Aquarium Corporation in 2006, found that discard mortality in dogfish fell below 50% following trawl capture in the wild. The investigators concluded that, based on the relatively low percentage of dying animals following the 72-hour period and the acid-base recovery demonstrated by survivors, spiny dogfish are able to survive at a high percentage when faced with routine trawl-capture stress. Investigators suggested that additional work should address the effects of greater fluctuations in tow times, tow weights, seasonality, air and seawater temperatures, air exposure (in the lab and the field), capture modes (e.g., gillnetting), and physical and behavioral indices as primary study parameters. Investigators also felt the apparent influence of gender on dogfish mortality also required additional investigation under more controlled settings Increasing Survival of Juvenile Atlantic Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) in the Northwest Atlantic Demersal Longline Fishery This S-K Grant Program project, completed in 2004 by the New England Aquarium Corporation, was designed to build upon the selectivity work already conducted and investigate how different hauling strategies might affect wound size and juvenile groundfish survivability. Longline catch is usually removed from the hook by force: the fish is held in place with a gaff braced against two parallel steel cylinders placed vertically on the gunwale, allowing the hydraulic hauler to pull the hook through the fish s flesh. This process can inflict severe injury to the fish. To minimize these injuries, an alternate protocol was investigated. A two-handed flip over the barb of circle hooks produced a single hole in the oral cavity of the fish. When this flip method was compared to the snub procedure, no difference in survival after 72 hours was observed in sublegal-sized cod bycatch. Biochemical data gathered on a similar subset of these fish suggested that the protocols chosen to judge survival may have added a level of stress that could have confounded the results Increasing Juvenile Cod Bycatch Survival in a Northwest Atlantic Longline Fishery This S-K Grant Program project, completed in 2004 by the New England Aquarium Corporation, was designed to (1) augment the survival data already collected on juvenile cod bycatch caught by demersal longlines, (2) quantify mitigated survival of juvenile cod bycatch when treated by immersion in solutions of potassium chloride, (3) quantify the degree of physiological stress experienced by juvenile cod bycatch through the analysis of biological parameters in the blood, and (4) continue to solicit advice from longline fishermen relative to increasing the survival of groundfish discards. Longline fishing practices often remove bycatch from the hook by force: the fish is held in place with a gaff braced against two parallel steel cylinders placed vertically on the gunwale, allowing the hydraulic winch to pull the hook through the fish s flesh. This process can inflict severe injury to the fish and affect survival. In previous studies, fish dehooked by force were also found to have low serum levels of potassium ion. 8

17 In this study, the importance of the potassium ion concentration in the blood was examined. Normal seawater enriched with granular potassium chloride was tested for its mitigating effect on survival. When the survival of snubbed sub-legal sized Atlantic cod treated with potassium ion was compared to untreated fish, no difference was found after 72 hours. Biochemical data gathered on a subset of similar fish were analogous to previous studies Selectivity and Survival of Atlantic Cod and Haddock in a Northwest Atlantic Longline Fishery This S-K Grant Program project, completed in 1999 by the New England Aquarium Corporation, was designed to examine the selectivity of commercial hook gear to evaluate the claim that juvenile fish caught by hook have minimal stress and, consequently, better survival. Two studies were conducted. The first study compared the length frequencies of cod caught on 11/0 versus modified 15/0 circle hooks. The 15/0 circle hook was non-traditional because it was constructed of the same gauge wire as the 11/0 hook. This study found that the 15/0 circle hook retained the same number of legal cod yet caught few sub-legal cod. In the second study, juvenile cod were collected during experimental longline fishing operations during 1996 and Fish were removed from fishing gear either by a mechanical dehooking device (crucifier), or gently by hand. Survival rates were determined by placing the juvenile fish into large cages and returning them to the depth at which they were caught for a period of about 72 hours. The lowest survival figures were found for fish that were wounded by the crucifier. The focus of the research in the second study was to assess the longline fishery and the rate of mortality of sub-legal catch after the fish were in the cages for 72 hours. The results showed high mortality associated with capture using the 11/0 circle hook when the cod had their jaws broken or torn after passing through the crucifer. Mortality increased when predation by herring gulls was considered Current Projects Optimization of Gear Size and Post-Release Mortality Reduction in the New Jersey Summer Flounder Hook-and-Line Fishery This 2013 Bycatch Reduction Engineering Program (BREP) project, to be carried out by Farleigh Dickenson University, is designed to quantitatively determine the optimal hook sizes for anglers to land legal summer flounder, reduce the number of sub legal flounder caught (discards), and reduce the incidence of deep hooking associated with catch and release. This technological research study has been designed to directly reduce the number of flounder discards and post release mortality through optimization of gear size for both the commercial and recreational hook and line fisheries. These optimal size(s) will result in fewer discards and increase stock biomass through reduction of stress and potential mortality. These data will then be used to recommend selective gear regulations to reduce future discard mortality. 9

18 Elucidating Post-Release Mortality and Best Capture and Handling Methods in Sublegal Atlantic Cod Discarded in Gulf of Maine Recreational Hook-and-Line Fisheries This 2012 BREP grant project, being carried out by the New England Aquarium Corporation, is designed to estimate 30-day post-release mortality of Atlantic cod using ultrasonic telemetry. This project also is designed to determine and disseminate best angling and handling practices that minimize injury/stress and enhance survival in sub-legal (and barely legal) cod discarded in Gulf of Maine recreational hook and line fisheries. The work will first evaluate the condition of ~400 cod immediately following capture by recreational angling during the summer of Prior to release, acoustic transmitters equipped with depth sensors will be affixed to a subsample of 150 individuals to detect any delayed fatalities for ~30 days post-release. Through pilot work, this project s researchers have field-tested the application of this technology to estimate mortality in cod and have found a clear disparity in acoustically transmitted depth profiles between live and dead specimens monitored over a ~2-week period. These initial findings, coupled with the generally small-scale movements of juvenile cod, indicate that, with careful placement of an array of acoustic receivers, this technology can reliably estimate post-release mortality for this species and size class. By retrospectively evaluating the physical, biological, and other variables from the capture and handling process, this project s researchers hope to establish a set of guidelines to reduce post-release mortality Evaluating the Condition and Discard Mortality of Skates Following Capture and Handling in the Sea Scallop Dredge Fishery This 2012 Atlantic Scallop Research Set-Aside project is designed to investigate the speciesspecific immediate and post-release mortality rates for little (Leucoraja erinacea), winter (Leucoraja ocellata), and barndoor (Dipturus laevis) skates. Mortality rates will be quantified using the combination of mortality predictors (i.e., condition and reflex impairment) and 72-hour mortality trials in an on-deck tank system (equipped with a chilling system to mimic bottom water temperatures). Condition index values will be based on visual assessment evaluating overt physical trauma on a scale from 1 to 3. Reflex impairment will be based on five reflexes scored on a present/absent scale (0 = reflex impairment; 1 = reflex exhibited) and then calculated into a vitality score as: 1 (# of reflexes exhibited/total # of reflexes tested). In addition, this study will assess the effect of factors such as fishing conditions (e.g., season and depth) and practices (e.g., tow times, volume of catch, deck duration) on post-release mortality. Quantitative information gathered from this study on post-release mortality can be applied to overall discard morality estimates in the New England scallop dredge fishery, which in turn will strengthen the reliability of future management models. As of August 2013, 3,731 skates (little: 2,292; winter: 1,184; barndoor: 255) had been sampled from five separate research trips ( ). Based on predictive condition and vitality (reflex-based) indexes, preliminary data suggest that a species-to-species difference exists in post-release mortality, such that barndoor skates are most vulnerable and winter skates are most resilient. 10

19 Post-Release Survivability of Longline-Caught Large Coastal Sharks This 2009 S-K Grant Program project, carried out by the University of Massachusetts, Dartmouth, was designed to increase the understanding of capture-related stress and the potential long-term effects on survival with a focus on sandbar and dusky sharks captured in the commercial demersal longline fishery. For each captured fish, blood and tissue samples would be gathered to quantify the capture-related physiological, biochemical, and molecular stress responses, with selected fish tagged to correlate stress parameters of a fish with its post-release movement patterns and long-term survival The Immediate and Short-Term Post-Release Mortality of Species in the Northwest Atlantic Skate Complex Captured by Gillnet and Otter Trawl This 2008 S-K Grant Program project, carried out by the New England Aquarium Corporation, aimed to quantify the species-specific at-vessel and short-term discard mortality rates from trawl and gillnet capture for skates in the Northeast Skate Complex. The analyses were designed to consider not only the impacts of fishing conditions (e.g., season, depth, and seawater and air temperature), but also fishing practices (e.g., tow/soak times, sorting durations/deck times, and handling protocols (i.e., picking versus non-picking)). In addition to generating data of great interest to management of species in the complex, this study was designed to expand the limited body of field-oriented stress investigation in elasmobranch fish. 3.2 Southeast Past Projects Fine-Scale Behavior and Mortality in Post-Release Carcharhinid Sharks in the Florida Recreational Shark Fishery This 2011 Cooperative Research Program project, carried out by Mote Marine Laboratory, was designed to quantify post-release mortality and behavioral effects of capture on blacktip sharks (Carcharhinus limbatus) caught in the Florida recreational shark fishery, and empirically test the differential impacts of circle versus J hooks on physiology and mortality. Investigators recorded capture measures (e.g., fight time, animal condition, etc.); tested blood stress indicators; and applied acceleration data loggers (ADLs) to measure fine-scale swimming behavior of blacktip sharks (N=31) caught by recreational fishermen. Mortalities (N=3, 9.7%) all took place within 2 hours (h) after release and were indicated by static depth data and the cessation of tail beat activity. Surviving sharks were monitored for 7 to 72 h (30 ± 22 h, mean ± SD) using ADLs. ADL data were used to calculate 58 metrics of fine-scale swimming behavior and evaluate their ability to indicate a recovery period in surviving sharks. Investigators used nonlinear mixed modeling to fit a four-parameter logistic function to these metrics. Of the 58 metrics, 18 displayed a significant logistic relationship with time after release, with mean recovery periods from each metric ranging from 7.4 to 14.4 h after release (9.9 ± 1.9 h, mean ± SD). 11

20 Overall, results show the ability of accelerometers to provide definitive information on animal outcomes and the broad applicability of these data to the study of post-release mortality and recovery in coastal sharks. Further work is needed to determine relationships between ADLbased metrics of recovery and blood biochemistry. This study did not address differences in handling practices between fishermen, such as the practice of removing the shark from the water to remove the hook or take photographs before release. However, for sharks left in the water throughout the handling process, study findings indicate low mortality for blacktip sharks caught in the recreational fishery and little effect of hook type on mortality rate or other parameters Post-Release Survival and Habitat Utilization of Juvenile Swordfish in the Florida Straits Recreational Fishery This 2010 Cooperative Research Program Project, carried out by Nova Southeastern University, was designed to investigate two main topics: (1) the post-release survival rates of juvenile swordfish after being released from the recreational rod and reel fishery and commercial swordfish buoy gear fishery in the Florida Straits, and (2) the habitat utilization of juvenile swordfish following release. High-resolution pop-up satellite archival tag technology was used to estimate the post-release survival of 16 individual juvenile swordfish captured with standard recreational or buoy fishing gear and techniques in the southeast Florida swordfish fishery. Five of the 14 reporting tags showed mortality within 48 hours, for a release mortality rate of 35.7%. However, no common thread could be found among the five mortalities. Results of the Release Mortality program indicated that if the true mortality rate was 35.7%, approximately 1,800 tags would need to be deployed to increase the precision of the mortality estimates to +/- 5% of the true value Evaluating the Effect of Barotrauma on Regulatory Discards in the Red Snapper Fishery using Advanced Acoustic Telemetry and Hyperbaric Experimentation This 2010 Marine Fisheries Initiative (MARFIN) project, carried out by Texas A&M University Corpus Christi, was designed to: (1) examine the long term impacts of barotrauma on red snapper discards using state-of-the-art ultrasonic telemetry after single and multiple recompression events, determining the validity of mark and recapture experiments in this fishery; and (2) identify the impacts that multiple barotrauma events have on the biology of red snapper under experimental laboratory settings using hyperbaric chambers. Specifically, this study was designed to (1) compare behavior and mortality of red snapper experiencing barotrauma using acoustic telemetry; (2) determine the relationship between previous estimates of discard mortality and mortality rates derived from internally implanted acoustic telemetry tags; and (3) examine the impact of multiple decompression events on red snapper growth, mortality, reproductive potential, and behavior under laboratory settings Collaborative Research to Quantify and Reduce Bycatch Mortality of Blacknose Sharks in Shrimp Trawls During this 2010 Cooperative Research Program project, University of Georgia Marine Extension Service staff worked with Georgia Department of Natural Resources biologists and commercial shrimpers to (1) understand commercial trawler interactions with blacknose sharks 12

21 using trained observers to collect data and (2) quantify the shark bycatch reduction potential of the newly certified Big Boy turtle excluder device (TED) with narrow 2 bar spacing compared to a Double Cover TED with standard 3.5 bar spacing (the industry standard), with fisheyes removed from both nets. This project was designed to involve commercial shrimpers throughout all stages of the project. Results indicate that the Big Boy TED with 2 bar spacing significantly reduces shark bycatch without affecting shrimp retention. Data collected on commercial shrimp trawlers indicate that blacknose sharks do not represent a large component of total shark bycatch in Georgia. The most common shark species captured were Atlantic sharpnose, bonnetheads, and scalloped hammerheads. On the commercial vessel with the most complete observer coverage (F/V Sundown, with 294 observed 2-hour trawls over a period of 2 years), the encounter rate for blacknose sharks was 11.9%. This vessel was fishing four nets simultaneously. The catch per unit effort was less than one blacknose shark per day (0.8). A total of 92 blacknose sharks were captured by this vessel in Blacknose sharks were encountered primarily in May and June when Georgia state waters are newly opened to commercial shrimping (0-3 miles); this is the time of year when blacknose occur near shore within the small size range that makes them vulnerable to trawl gear Release Mortality of Gulf of Mexico Greater Amberjack from Commercial and Recreational Hand-Line Fisheries This 2009 MARFIN project, carried out by the University of Florida, yielded several results. During this study, greater amberjack were discovered to have a self-venting mechanism unheard of in other physoclistous reef fishes. Venting does appear to assist greater amberjack when captured from deeper depths, usually deeper than 150 ft. Amberjack may be good candidates for venting because their swim bladders are tough and are buttressed by their ribs. Overall, greater amberjack seem to survive capture and release much more easily than most other reef fishes. This may be because they are really semi-pelagic, and although they aggregate around structure, similar to reef fish, they also use the water column from the surface to great depths in a matter of minutes. This project indicated a high acute survival rate for greater amberjack for some handline fisheries, and initially depth of capture and decompression do not appear to be major factors in release or discard mortality. There are several possible explanations as to why acute barotrauma may not be high in amberjack. First, greater amberjack cannot be brought up as quickly to the surface as other fish, such as gag grouper or red snapper, because they energetically resist being brought up (hence their attribute of being great fighting fish). This may give the fish time to re-absorb oxygen from the swim bladder into the blood stream. Second, the membrane of the swim bladder is very thick in amberjack and is internally baffled, which would provide greater structural support. Finally, the self-venting mechanism is the main contributor to off-gassing of the excess gases expanding in the swim bladder. 13

22 Characterization of Recreational Discard Composition and Mortality Rates for Gray Snapper and Other Estuarine-Dependent Reef Fishes within a Gulf Coast Estuary and Nearshore Florida Waters This 2009 Cooperative Research Program project, carried out by the Florida Fish and Wildlife Conservation Commission, was designed to characterize recreational discard mortality rates for gray snapper captured within a gulf coast estuary and nearshore Florida waters and to develop sampling methods to more effectively collect detailed recreational catch, effort, and disposition data for gray snapper and other estuarine-dependent reef fishes. Discard mortality experiments indicated that mortality rates for gray snapper (Lutjanus griseus) in the lower Tampa Bay estuary (inshore) and neighboring Gulf of Mexico waters (nearshore; 20 nm from shore) were relatively low. A total of 247 gray snapper were caught over nine inshore and nearshore experiments; 17 of these fish died within 48 hours, for an overall mortality rate of 6.9%. The inshore mortality rate (1.4%) was lower than the nearshore mortality rate (14.4%) and was probably related to depth of capture. Hook position and increasing depth significantly influenced the probability of mortality. Gag (Mycteroperca microlepis) were also retained during inshore mortality experiments; a total of 111 gag were caught over four experiments, and eight of these fish died within 48 hours leading to an overall mortality rate of 7.2%. Hook position and decreasing size of the individual significantly influenced the probability of gag mortality. For both species, individuals hooked in the lip were most likely to survive the catch and release event, while gray snapper hooked in the esophagus or gag hooked in the gills were the least likely to survive. The short-term mortality rates calculated during this study are relatively low and are conservative estimates due to responsible handling practices; these rates may increase depending on depth captured, fish size, and the position of the hook in each fish. Directed hook and line sampling was conducted each month in inshore and nearshore Tampa Bay waters from July 2009 to July The use of circle hooks during our study resulted in a high percentage of reef fish being hooked in shallow anatomical locations such as the lip or inside the mouth (94.6%). A large proportion (95.7%) of all fish caught was reported to be released in good condition Survival of Discarded Reef Fish Species in the Recreational Fishery Using At-Sea Observer Surveys and Mark-Recapture Methods off the Florida Coast in the Gulf of Mexico This 2009 Cooperative Research Program project, carried out by the Florida Fish and Wildlife Conservation Commission, was designed to evaluate survival of discarded reef fish from recreational for-hire headboats operating in the Gulf of Mexico. Based on behavioral observations at the surface immediately upon release, the majority of reef fish discarded in this study were able to break the surface and swim out of sight immediately (good condition) or relatively quickly after some minor disorientation (fair condition). More than 90% of discarded gag and red grouper and more than 80% of scamp were released in good condition. Compared to grouper species, a higher percentage of red snapper and vermilion snapper were visibly struggling at the surface and were often unable to submerge (poor condition), or were unresponsive and presumed dead (dead condition) upon release. Red snapper caught on circle 14